HELP Image resolution on LR6 for good quality 8"x10" pictures

[Hjalmarg1]

Hi,
to all who live from taking pictures to wedding and First Communion events and later printing, I would like to ask you what resolution parameters you use to get high-quality printing?
A friend of mine suggested 4,500x3,600 pixels (vertical x horizontal) and 240 dpi. Could I use these settings?

Likewise, if I would like a A3 size printing, should I use the same settings?

Thanks and regards

 

[Skirball]

A friend of mine suggested 4,500x3,600 pixels (vertical x horizontal) and 240 dpi. Could I use these settings?

Nothing personal to your friend, but if that's what recommends, he probably shouldn't be recommending print settings.

It's not terrible complicated: resolution (in inches) x dimension (in inches) = length (in pixels). So if you wanted to print an 8 x 10 at 240 dpi simply multiply the resolution times length and width:

240 x 8" = 1920
240 x 10" = 2400

Optimal image size = 2400 x 1920

That said, most printers can do 300 dpi, and good ones much more. As a rule of thumb I'd aim for 300 dpi, or a 3000 x 2400 image.

Note: the size he recommended, 4500 x 3600, at 240 dpi, would make a 18.75 x 15" image.

 

[Mt Spokane Photography]

You will get lots of answers, many are partially correct. The subject is complex, and if you want to really know, its also printer specific and viewing distance is a huge factor. Some printers want more or less DPI.

300 DPI is a safe number, but you can use 360 PPI with Epson photo printers, even 720 PPI.

The printer will adjust the number of pixels needed to print at the selected size as it processes the image.

Obviously, you can try to outsmart the printer and do the computation yourself. It can backfire if you calculate wrong.

Here is a good writeup on the subject.

BTW, your friends advice will work fine, for a viewing distance of 3 ft, 191 ppi is optimal.

 

[Skirball]

BTW, your friends advice will work fine, for a viewing distance of 3 ft, 191 ppi is optimal.

That's not what his friend's advice was. It was for 4500 x 3600 at 240 dpi; which will not give the desired size of 8" x 10". But as you said, you'll get lots of answers, many partially correct.

 

[Hjalmarg1]

You will get lots of answers, many are partially correct. The subject is complex, and if you want to really know, its also printer specific and viewing distance is a huge factor. Some printers want more or less DPI.

300 DPI is a safe number, but you can use 360 PPI with Epson photo printers, even 720 PPI.

The printer will adjust the number of pixels needed to print at the selected size as it processes the image.

Obviously, you can try to outsmart the printer and do the computation yourself. It can backfire if you calculate wrong.

Here is a good writeup on the subject.

BTW, your friends advice will work fine, for a viewing distance of 3 ft, 191 ppi is optimal.

Many thanks to Skirball and Mt Spokane for your clarification. Now I understand the logic and that 240 dpi might be a bit low resolution.
AS per your suggestions, it seems to be that a safe number is something between 300dpi and 360 dpi for 8"x10" prints as I want to deliver.